Here you will find 3 different ways to play Shen like the ultimate tank.

Shen with extra dmg
Shen with extra magic resist
Shen as a normal Tank

PROS:
-Always hard to kill
-Good all-round AD counter
-Small count of counters
-Support Ulti for saveing


Cons:
-Weak dmg in early game
-Strong counters (like Jayce)
-Long cooldown for his E in Early-Mid game
-High energy cost

If you got a premade Team, you can easly save your friend from death with your ultimate.

If you aren't a premade Team and you joined random a team, you should always keep an eye on your allies.
When you shield your allied (R) then taunt (E) the enemy imidietly after your arriving and shield yourself (W) and easy pick up a kill (with Q ; Ki strike and auto hit)

Farming with Shen is quite easy, but you need the right timing.

You can last-hit the minions with auto-hit or Ki strike.
If the minions are further away, you can also kill them with your Vorpal Blade (Q).

And never forget:
You can heal you up with your Vorpal blade.
Then you dont need health pots so often and you can stay longer on lane